Ordinary glass used for making household windows, mirrors, etc. Such glass contains many impurities compared to the far more transparent optical glass used by better manufacturers for making optical components.
This is easily demonstrated by holding a piece of window glass and looking at the edge. The glass will appear to have a greenish tint - it wont be clear. Unfortunately, many cheap lens filters are made with poor-quality window glass.
cf. optical glass, transparent.
Entry last updated 2002-04-27. Term 1310 of 1487.
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